Manufacture of artificial thread from solutions of cellulose.



UNITED STATES PATENT OFFICE.

RUDOLF LINKMEYER, OF HERFORD, GERMANY MANUFACTURE OF ARTIFICIAL THREAD FROM SOLUTIONS OF CELLULOSE.

Specification of Letters Patent.

Patented April 30, 1907.

Application filed March 29, 1905. Serial No. 252.633.

' of cellulose threads presenting a luster rcsembling that of silk and obtained by the solution of cellulose in a cupro-ammoniacal liquor and precipitation of the cellulose from its solution after this latter has been passed through small apertures.

It is known that cellulose cannot be dissolved directly in the state of concentration necessary for permitting of preci itation and a large number of processes are a ready in existence for the preparation of concentrated solutions. The greater number of these processes are complicated and are based u on the reactions of concentrated alkalies tliey do not always give the desired result, the strong alkalinity of the solutions is detrimental to th ubsequent treatment of the threads and the thickness of these solutions renders their filtration difficult.

The present invention has for its object a process which ermits of rendering cuproammoniacal so utions of cellulose directly utilizable for the precipitation of the cellulose in the form of threads, by a reduction of the proportion of ammonia that they con tain.

It has been found that it is possible to extract from a cellulosic cupro-ammoniacal solution a very large part of its ammonia, without any precipitation of the dissolved cellulose taking place, and this may be explained, if we admit that the ammonia is partially liberated by the fact of the dissolution itself. This extraction of the ammonia may be effected by suction by creating a vacuum above the solution and agitating the mass so a as to facilitate the liberation of the gas; or

this separation may be effected in contact with the air, by mixing the mass and in in' jecting into it, for example, a current ofair. The exactness of the assumption that a portlon of the ammonia is liberated as a result of the dissolution of the cellulose, would" appear to be demonstrated by the fact that 'it in water.

if in a very com lete vacuum'a bath of am moniacal oxid of copper is freed from all the ammonia not combined with the oxid of copper, cellulose then being dissolved therein, it is found, upon re-esta'blishjng the vacuum above the bath, that large quantities of ammonia gas are again liberated.

Hitherto, in the ammoniacal oxid of copper processes, the whole of the ammonia has been left in the solution of cellulose in order to subsequently precipitate it in the form of a salt corresponding to the acid employed, when it was desired to solidify the threads. The recovery of the ammonia contained in these salts (mostly acid) mixed with salts of copper, occasioned rcat expenditure and ne cessitated the emp oyment of special processes for again'liberating this ammonia. In the present process, this ammonia is' in great part collected, in a gaseous state and chemically pure, by simple suction; it is therefore possible to immediately redissolve If it is considered that, in order to dissolve 1000 grams of cellulose, about 3000 to 3500 grams of ammonia are reiiired, and further that, as a result of losses, tiere are used with the processes hitherto employed about 4500 grams of ammonia per kilogram of artificial thread, it will be obvious that the present process is of great practical value.

After the elimination of the uncombined ammonia, the solution is capable of being drawn into threads which solidify very rapidly in air. These threads may therefore be treated in various ways in order to convert them into threads of artificial silk.

What I claim and desire to secure by Letters Patent of the United States is 1. A process for the preparation of cuproammonlacal solutions of cellulose for the purpose of manufacturing artificial threads, consisting in withdrawing from these solutions a portion of their ammonia before converting above the solution and extracting the am- In testimony whereof I have hereunto set inonia by suction. J

4. A process for the extraction of ammonesses this 14th day of March 1905.

niii from a cupro annnoniacal solution of cel- RUDOLF LIN KMEYER.

lulose, consisting in creating a vacuum above Witnesses:

the solution, stirring or mixing this latter RQV. V. K1 RKPATRIOK,

and extracting the ammonia by suction. I J. V. KIRKPATRICK.

myliand in presence of two subscribing it- 

